Structural panel for a steam generator



P 1968 A. BRUNNER 3,402,700

I STRUCTURAL PANEL FOR A STEAM GENERATOR Filed July 22, 1966 4 Sheets-Sheet l I n venfar: A LFRED BRUNNER 1 A TTONEVS Sept. 24, 1968 v BRUNNER 3,402,700

STRUCTURAL PANEL FOR A STEAM GENERATOR Filed July 22, 1966 4 Sheets-Sheet 2 I nvenlor: A 1. FRED BR UNNER A. BRUNNER STRUCTURAL PANEL FOR A STEAM GENERATOR Sept 24, 1968 4 Sheets-$heet 3 Filed July 22, 1966 38 I nveniar: A; FRED BRUNNER BY A. BRUNNER Sept. 24, 1968 STRUCTURAL PANEL FOR A STEAM GENERATOR Filed July 22, 1966 4 Sheets-Sheet 4 [3 Fig- 6 Inventor:

A L FRED BRUNNER ATTO EVS United States Patent 3,402,700 STRUCTURAL PANEL FOR A STEAM GENERATOR Alfred Brunner, Winterthur, Switzerland, assignor to Sulzer Brothers, Limited, Winterthur, Switzerland, a corporation of Switzerland Filed July 22, 1966, Ser. No. 567,133 Claims priority, application Switzerland, July 22, 1965, 10,313/ 65 7 Claims. (Cl. 122-6) ABSTRACT OF THE DISCLOSURE The panels are disposed about the chamber walls of the .steam generator in order to support the walls against outward bulging under the forces generated in the interior of the chamber. The tie bars maintain the panels in position about the chamber. The panels can also have parallelogram surfaces which are formed with pectinated free edges in order to damp sound vibration.

This invention relates to a structural panel. More particularly, this invention relates to a thermally stressed wa'll constructed with structural panels.

Generally, the chambers of a steam generator have been lined with walls constructed of tubes which are used to carry a heated working medium. Since the pressures acting on such tube Walls are generally greater on the inside than the outside, the tube walls have been supported circumferentially by a system of girders which are tied together so as to resist the outward expansion forces imposed on the tube walls.

However, in many instances, the portions of the tube walls between adjacent girders have been left in an unsupported condition due to a spacing between these girders. Because of this, these unsupported portions have been subjected to localized'bending forces from the pressure within the steam generator chamber. In addition, these unsupported portions of the tubes have been subjected to localized thermal stresses from the heated working medium flowing through the tubes. Thus, in many instances, since the superposition of these bending forces and thermal stresses would otherwise result in a total stress which exceeds the maximum strength of the tube portions, either the walls of the tube portions have been made thicker or the temperature of the heated flow medium has been reduced in order to withstand or reduce the superimposed bending forces and thermal stresses. However, in the case of using a thicker wall in the tubes, the total weight of the tube walls has'become greater. Also, in the case of reducing the temperature of the heated flow medium, the capacity and efficiency of the steam generator have been reduced.

Further, due to the necessary bulk and size, the girders which have been used to support and restrain the tubular walls have required relatively large spaces outside the useful working space of the tube walls of the steam generator. Thus, the overall space requirements of the steam generators have been relatively substantial. Also, where the girders have been placed closer together to reduce localized bending, the girder systems have become prohibitively heavy and massive.

Accordingly, it is an object of the invention to restrain the tube walls of a steam generator against buckling.

' It is another object of the invention to support and restrain'the walls of a steam generator within a relatively limited space. v

It is another object of the invention to reduce the weight and size of the restraining members supporting the walls of a heated chamber against buckling.

It is another object of the invention to maintain the Wall thickness of the tubular portions of a tube Wall at a minimum thickness while maintaining the temperature of a heated medium flowing through the tubular portions at a maximum.

It is another object of the invention to provide a structural panel having sound and/ or heat insulating properties.

Briefly, the invention provides a steam generator having chamber walls formed of interconnected heat carrying tubes with an enclosure for the walls formed of structural panels. The structural panels are disposed to the exterior of the chamber walls so as to support the walls against outward bulging or buckling. The panels are formed of a minimal total thickness so as to function within a limited space such that for a given steam generator output, a smaller overall space is occupied as compared to the heretofore steam generator structures. In addition, the panels are extended across substantially the entire exterior surface of the chamber walls so as to support all the surface of the chamber walls.

The panels are made of materials in a manner such that the overall weight of the panels in the steam generator installation is maintained as a minimum.

Generally, the structural panel of the invention is composed of at least one areal structure sandwiched between a pair of flat sheets. The areal structure is formed by skewed parallelogram surfaces inclined relative to a plane parallel to the areal structure. Because of this structure the structural panels possess the properties of a spatial lattice thereby allowing the panels to have a wide range of application. For example, since the structural panels have a good load-supporting capacity as well as a simplicity of design which permits easy fabrication, the panels are useful as structural panels in building construction and carpentry. In addition, the panels provide good sound and/or heat insulating properties.

Further, the panel of the invention is suitable as a packaging material since it combines adequate stability with a relatively low weight, especially When made of plastics or board. Also, the panels of the invention may be used in the construction of steam generators to serve as plane surface walls in supercharged boilers.

These and other objects and advantages of the invention will become more apparent from the following detailed description and appended claims taken in conjunction with the accompanying drawings in which:

FIG. 1 illustrates a View taken on line A-B of FIG. 2 of a first embodiment of a panel according to the invention;

FIG. 2 illustrates a view taken on line C-D of FIG. 1;

FIG. 3 illustrates a diagrammatic view of a steam generator in which panels of the invention are employed as a covering;

FIG. 4 illustrates the disposition of the panels on a combustion chamber wall of the steam generator of FIG. 3;

FIG. 5 illustrates a view taken on line K-L of FIG. 4;

FIG. 6 illustrates a modification of the panel of the invention;

FIG. 7 illustrates another modification of the panel of the invention;

FIG. 8 illustrates another modification of the panel of the invention;

FIG. 9 illustrates a view taken on line E-F of FIG. 10 of an embodiment modified relative to the modified panel of FIG. 8; and

FIG. 10 illustrates a view taken on line GH of FIG. 9 rotated through in the drawing plane.

Referring to FIGS. 1 and 2, the panel 1 consists of two plane sheets 2 and 3 between which an areal structure 4 is disposed which is permanently connected with the sheets 2 and 3, for example, by means of welding, brazing or glueing. The areal structure 4 consists of skewed parallelogram surfaces 5 which are inclined relative to each other and relative to a plane disposed parallel to the areal structure. Two adjacent parallelogram surfaces 5 abut in the plane of intersection C-D at an edge 6 which is inclined at an angle ,6 (FIG. 2) relative to the plane extending in parallel to the areal structure and amounting to 45. The parallelogram surface may have an acute angle 7 of 52 and an obtuse angle 6 of 128. These two angles are not directly indicated in FIG. 1 because the surfaces 5 are not disposed in the drawing plane. The two angles 7 and 6 result in a conjoint angle a which in this case amounts to approximately 60. The panel 1 is suitable for absorbing bending moments, point loads, and loads which are uniformly distributed over the panel surface.

Referring to FIGS. 3, 4 and 5, a plurality of panels 1 are secured to the sides of a steam generator 29 in which combustion takes place in a combustion chamber at positive pressure; the steam generator therefore being a supercharged boiler. The combustion chamber of the steam generator 29 is suspended on a supporting frame 30 (FIG. 3) by means of supporting rods or supporting pipes 31 through which the working medium of the generator flows. The combustion chamber is bounded by pipes 32 which iii are closely welded to each other, preferably via the fins or connecting webs 33 (FIGS. 4 and 5) disposed between the individual pipes. Ties 34 which extend in parabola form over each of the walls of the combustion chamber and which are preferably connected with each pipe 32, for example by welding, are provided on the side of the combustion chamber pipes facing away from the firing system and are uniformly distributed over the height of the combustion chamber.

Referring to FIG. 4, each panel 1 extends over the entire width of a combustion chamber wall and is retained at each end by the ends of a pair of ties 34 of the combustion chamber wall perpendicular thereto. The ties 34' parallel to the retained panel 1 are positioned inside the retained panel. The steam generator is thus completely surrounded by panels 1 which may consist of steel or aluminum plate and which prevent the plane pipe walls of the combustion chamber from bulging due to the effect of the positive pressure.

In order to connect the ties 34 with the panels 1, the edges of the panels 1 are provided with inclined slits 35 through which the ends 36 of the ties 34 extend. The ends 36 of the ties 34 are hook-shaped to mount rollers 37 therein which engage the panels 1. In addition, insulating bricks 38 are provided between the panels 1 and the wall formed by the pipes 32 with Z-shaped retaining plates 39 disposed between every two superjacent bricks. The length of the legs of each plate 39 is longer than half the height of the insulating bricks so that the upper leg of a lower retaining plate and the lower leg of an upper retaining plate overlap to some extent. The insulating bricks 38 are so disposed that several superjacent rows are retained in each case by one panel 1. The adjacent bricks between two superjacent panels 1 are not connected to each other by means of Z-shaped retaining plates, instead plates 39 and 39 are provided for surrounding the bricks of the lowest or uppermost row on the underside or upperside respectively. The insulating bricks 38 are provided with hollow spaces in order to minimize the weight of the bricks.

The panel may also be advantageously employed as bottom panel, for example for covering a hollow space disposed below floor level; the panel being preferably made of metal, for example steel or aluminum plate.

The optimum dimensions of the angles a and B, the height h of the areal structure, the strip width b, the longitudinal division 0, the wall thicknesses s s and s (FIG. 2) may be determined in accordance with the spans along the principal directions of the panel, the total load- 4 ing, the maximum surface loading and the properties of the material, for example by empirical means.

Referring to FIG. 6, two areal structures 7 and 8 are disposed between two fiat sheets 2 and 3 to form a panel. In this modification the areal structures 7, 8 are shaped differently in that they have different heights while having the same angle of inclination 5. Also, the areal structure edges which face each other are connected by means of a third fiat sheet 9. The two areal structures 7 and 8 are disposed so that the conjoint angles at of both structures extend in the same direction. However, depending on the purpose of the structure, the conjoint angle a of the areal structure 8 may extend in the opposite direction to the conjoint angle on of the areal structure 7, for example, when the panel is used as a bottom panel to which a point load is applied. Depending on requirements, the panel can be increased in size by the attachment of one or more areal structures to the upper sheet 2 or to the lower sheet 3 in order to improve the ability to support point loads.

Referring to FIG. 7, two identically formed areal structures 11 and 12 are joined to form a panel without a separate sheet therebetween. The areal structures 11 and 12 are therefore disposed together between the two sheets 2 and 3.

Referring to FIG. 8, three areal structures 15, 16, 17 are combined between two sheets 2 and 3 into a panel. The three areal structures have the same conjoint angle a, the same strip width 6 and the same longitudinal pitch c. While the two areal structures 15 and 17 have the same height and are each directly connected with one of the two sheets 2 and 3, the third areal structure 16 disposed between the structures 15 and 17, has a larger angle of inclination B and a larger height than the structures 15 and 17. The areal structure 16 is so disposed between the areal structures 15 and 17 that the edges 19 between two parallel surfaces of one side each of the areal structure 16 are connected with corresponding edges 20 of structure 15 and 17 respectively; the edges 20 being mounted on sheets 2 or 3 respectively. A panel of this kind can be conveniently employed as insulation against heat and/or sound.

Referring to FIGS. 9 and 10, a panel corresponding in fundamental construction to that of the panel according to FIG. 8 provides the free edges 22 of the areal structures 15 and 17 with cuts 26 so that the edges 22 are pectinated thereby making the panel particularly suitable for applications in which sound vibrations are to be damped. The cuts 26 are dimensioned so that the natural flexural frequency of the teeth remaining between the aforementioned cuts fall within the range of the vibrations to be attenuated. The disposition of the teeth is preferably modified so that the teeth respond to an entire frequency spectrum. Upon excitment of the panel by external vibrations, the teeth vibrate in resonance so that vibrational energy is absorbed due to friction in air.

In a further embodiment of the invention, the spaces formed between the areal structure or the areal structures and the sheets may be filled with liquids, powders, fiber bulk or foam substances. Such fillings may then improve the thermal insulation or sound attenuations or increase the thermal inertia. The aforementioned spaces ma also be employed for the conduction of liquid or gaseous thermal transfer media or electric heating units may be mounted into these spaces.

An embodiment of the invention is so constructed that the material of at least one of the sheets is different from the material of the areal structure. Thus, it is possible to combine mechanical properties with aesthetic features, for example when the panel of the invention is employed as a structural panel and a first sheet or both sheets are used as room facings, the sheets can be constructed from a plastic panel provided with a design and the areal structure can be constructed of metal. Further, where one sheet consists of a light alloy plate, with an anodically oxidised external surface, such a panel can also be employed for facades.

Depending on the material employed the areal structures may be produced by folding, pressing, deep-drawing, vacuum forming or extruding.

The panels may be constructed not only from homogeneous materials such as metals and plastics but also sintered materials or fibers or chips, such as fiber glass, wood fibers, wood chips etc. which are bonded by plastics. Panels made of wood fibers and wood chips bonded by plastics can be employed in carpentry, for example for doors.

Having thus described the invention, it is not intended that it be so limited as changes may be readily made therein without departing from the scope of the invention. Accordingly, it is intended that the subject matter described above and shown in the drawings be interpreted as illustrative and not in a limitin sense.

What is claimed is:

1. In combination with a steam generator having plurality of walls bounding an enclosed chamber, each said wall including a plurality of tubes for conveying a heated medium; a plurality of structural panels disposed about the exterior of said walls to enclose said walls, each of said structural panels comprising a pair of spaced parallel plane sheets, and at least one areal structure disposed between said plane sheets in fixed relation thereto, said areal structure having a plurality of surfaces disposed at angles relative to said plane sheets, and means for securing said panels in place about said walls whereby said panels support said walls against outward bulging due to a higher pressure in said chamber than outside said panels.

2. The combination as set forth in claim 1 wherein said means for securing said panels include a plurality of tie 6. The combination as set forth in claim 1 which further comprises heat insulation means between said walls and said panels.

7. The combination as set forth in claim 1 wherein said parallelogram surfaces of at least one of said panels are skewed with respect to each other.

References Cited UNITED STATES PATENTS 1,644,199 10/1927 Moore 52615 XR 2,120,129 6/1938 Hardgrove et al 122-6 2,700,403 1/1955 Herschell 52615 X 2,959,257 11/1960 Campbell 52-615 XR 2,963,128 12/1960 Rapp 52630 2,983,038 5/1961 Johnson 52615 XR 3,086,625 4/1963 Wyatt 52615 X 3,108,924 10/1963 Adie 526.5 X

KENNETH W. SPRAGUE, Primary Examiner, 

